The growing power of machines, increased output per face, higher degree of mechanization and safety of all operations involved in the use of a mechanized complex pose a problem of developing an advancing system with high power, kinematic and performance parameters and a high standard of safety.
The widely employed advancing systems incorporating chain traction assemblies fail to ensure the required parameters and are replaced by chainless haulage systems.
The widest recognition has been won by the haulage systems incorporating an advancing mechanism built into the machine and having a driving wheel and a traction element in the form of a rack with teeth fitted to the face conveyor.
The rack serves as a guide for the grips which prevent the cutting machine from displacement from the face conveyor and ensure the engagement of the driving wheel of the advancing mechanism with the traction assemblies.
The chainless haulage systems promote operational safety and ensure the required power and kinematic parameters. The built-in haulage units complicate the design of the cutting machine thereby worsening its performance and interaction with the other mechanisms of the complex due to absence of adjustment of the clearance between the machine and the support elements and between the machine and the face conveyor, i.e. in the area of handling of the mined mineral.
Considerable disengagement forces in the engagement the driving wheel and the rack, fluctuations of the geometrical parameters of engagement, rack gumming conditions result in a low efficiency of the haulage units and an unjustified increase of the drive power. The complexity and high labour content required to make a sufficiently accurate rack step up manufacturing costs.
The connection of the rack with the mining machine by the grips of the haulage unit imposes considerable transverse forces on the rack which complicates the fastening of the rack to the conveyor and impairs its engagement with the driving wheel.
Known in the prior art are the walking advancing systems of a coal shearer comprising the hydraulic cylinders for advancing the machine, guides for gripping the hydraulic cylinder during the pull-up motion, fixing elements and the hydraulic systems for grip and advancement control (UK Pat. No. 2.038.903).
The shearer is advanced in the known systems by the hydraulic cylinders which are secured to the shearer body while their rods are fastened on the slides coacting with the guide. The slides are fixed either by friction or by some latching means whose lugs enter the guide slots during alternate fixing of the slides. The slides are fixed along the guide by springs and released by hydraulic cylinders. The hydraulic system provides alternation of the operating cycles, i.e. fixing of the hydraulic cylinder on the guide and the advancement of the machine.
In the known cases the guide holds the shearer in a transverse direction and is used as a traction assembly of the advancing mechanism. The combination of the advancing and holding functions in a single construction, as well as fastening minimum two hydraulic cylinders to the cutter-loader defines the mechanism as a built-in one, i.e. as an integral part of the given machine.
The known systems of walking advancing mechanisms have a number of design and operational disadvantages.
The use of friction forces for fixing fails to provide the required reliability of locking the slides due to considerable changes in the state of contacting surfaces (water, oil, coal fines, etc.).
Another known advancing system of a coal shearer comprises a guide and an advancing mechanism consisting of advancing hydraulic cylinders, slides interacting with the advancing guide, a hydraulic system and control units (UK Pat. No. 1291427).
Among the disadvantages of the known device it is worth to mention the complexity of the gripping units, probability of spring gumming, wear of lugs and latches which decreases the reliability and safety of the advancing mechanism.
Fastening the guide on the pans of the face conveyor fails to guarantee the required accuracy of snapping of mechanical latches into the guide slots. As a result, the advancing forces are transmitted to the joints of the conveyor pans while the transverse forces of the shearer, to the advancing elements which decreases the reliability of the latter.
Fastening the hydraulic cylinders to the shearer decreases the reliability of fastening of the body joints since said joints are loaded by advancing forces.
The main object of the invention is to provide an advancing system of a coal winning machine wherein the novel design of the independent advancing mechanism and guide promotes the reliability of the entire system.